SARS-CoV-2 transmission in schools in Korea: nationwide cohort study.

Objective There is an urgent public need to readdress the school closure strategies. We aimed to describe the epidemiology of COVID-19 in schools and school-aged children to understand their roles in transmitting SARS-CoV-2 in Korea. Design Retrospective cohort study. Setting All schools in Korea Patients All school-aged children in Korea. Interventions None (observational study). Main outcome measures Incidence rate, proportion of affected schools. Results Between February and December 2020, the incidence rate was lower among school-aged children (63.2–79.8 per 100 000) compared with adults aged 19 and above (130.4 per 100 000). Household was the main route of transmission (62.3%), followed by community (21.3%) and school clusters (7.9%). Among the schools in Korea, 52% of secondary schools had COVID-19 cases, followed by 39% of primary schools and 3% of kindergartens. Conclusions We found that schools and school-aged children aged 7–18 years were not the main drivers of COVID-19 transmission. The major sources of transmission were households.